As it is generally known, various types of storage services can be used to provide external data storage from storage server systems (“storage systems”) to other computer systems. For example, Network-Attached Storage (NAS) systems provide file-based storage services over a network. File-based storage services provide external storage in the form of externally stored files, so that the files can be accessed as if they were located on local storage. NAS systems may use various specific protocols to provide file-based storage services, including but not limited to the Network File System (NFS) distributed file system protocol, the Server Message Block (SMB)/Common Internet File System (CIFS) application-layer network protocol, and/or Apple Filing Protocol (AFP).
Block-based storage services provide external storage in the form of blocks served by storage systems from remote disk storage devices. For example, block-based storage services may employ the Internet Small Computer System Interface (iSCSI). iSCSI is an Internet Protocol (IP)-based storage networking standard for linking data storage resources, and allows access to external storage from the storage system as if it were from a locally attached disk. Block-based storage services may also use Fibre Channel (FC) network technology, and/or the Serial Attached SCSI (SAS) protocol or the like in the context of Direct Attached Storage (DAS).
In order to improve the availability of storage services, user data may be replicated across multiple storage systems. In a basic configuration, an active storage system is used to provide one or more storage services, while a duplicate copy of the user data stored on the active storage system is concurrently maintained on one or more backup storage systems. In the event that the active storage system fails, one of the backup systems can seamlessly take over providing the storage services, thus improving continuity of service.